2. Machining Processes
Manufacturing Processes can be broadly divided into two groups:
a) Primary Manufacturing Processes : Provide basic shape and
size
b) Secondary Manufacturing Processes : Provide final shape and
size with tighter control on dimension, surface characteristics
Material removal processes once again can be divided into two groups
1. Conventional Machining Processes
2. Non-Conventional Manufacturing processes
3. Convectional Machining Processes
Conventional Machining Processes mostly remove material in
the form of chips by applying forces on the work material with
a wedge shaped cutting tool that is harder than the work
material under machining condition.
The major characteristics of conventional machining are:
• Generally macroscopic chip formation by shear
deformation
• Material removal takes place due to application of cutting
forces – energy domain can be classified as mechanical
• Cutting tool is harder than work piece at room
temperature as well as under machining conditions
4. Non-Convectional Machining Processes
Non-conventional manufacturing processes
is defined as a group of processes that
remove excess material by various
techniques involving mechanical, thermal,
electrical or chemical energy or combinations
of these energies but do not use a sharp
cutting tools as it needs to be used for
traditional manufacturing processes.
5. Non-Convectional Machining Processes
The major characteristics of Non-conventional machining:
2. In this process, there may not be a physical tool present. For
example in laser jet machining, machining is carried out by laser
beam. However in Electrochemical Machining there is a physical
tool that is very much required for machining
3. In this process, the tool need not be harder than the work piece
material. For example, in EDM, copper is used as the tool
material to machine hardened steels.
4. Mostly this processes do not necessarily use mechanical energy
to provide material removal. They use different energy domains
to provide machining. For example, in non conditional processing
mechanical energy is used to machine material, whereas in ECM
electrochemical dissolution constitutes material removal.
6. Classification of NCP processes
CLassification of NCP processes is carried out depending on the
nature of energy used for material removal.
1. Mechanical Processes
• Abrasive Jet Machining (AJM)
• Ultrasonic Machining (USM)
• Water Jet Machining (WJM)
• Abrasive Water Jet Machining (AWJM)
2. Electrochemical Processes
• Electrochemical Machining (ECM)
• Electro Chemical Grinding (ECG)
• Electro Jet Drilling (EJD)
3. Electro-Thermal Processes
• Electro-discharge machining (EDM)
• Laser Jet Machining (LJM)
• Electron Beam Machining (EBM)
4. Chemical Processes
• Chemical Milling (CHM)
• Photochemical Milling (PCM)
7. Needs for Non Traditional Machining
• Extremely hard and brittle materials or
Difficult to machine materials are difficult to
machine by traditional machining processes.
• When the workpiece is too flexible or slender
to support the cutting or grinding forces.
• When the shape of the part is too complex.
9. Abrasive Jet Machining
Abrasive Jet Machining (AJM), also known as micro-abrasive blasting, is
a mechanical energy based unconventional machining process used to remove
unwanted material from a given workpiece.
The process makes use of an abrasive jet with high velocity, to remove material
and provide smooth surface finish to hard metallic workpieces
11. Ultrasonic Machining(USM)
•This machining uses ultrasonic waves to produce high
frequency force of low amplitude, which act as driving
force of abrasive.
• Ultrasonic machine generates high frequency vibrating
wave of frequency about 20000 to 30000 Hz. This high
frequency vibration transfer to abrasive particle contains
in abrasive slurry.
•This leads indentation of abrasive particle to brittle work
piece and removes metal from the contact surface.
•USM for machining brittle work material
•Material removal primarily occurs due to the indentation
of the hard abrasive grits on the brittle work material.
14. Water Jet Machining
•A water jet cutter, also known as a water
jet or waterjet, is an industrial tool capable of cutting
a wide variety of materials using a very high-pressure
jet of water, or a mixture of water and
an abrasive substance.
• The term abrasive jet refers specifically to the use of
a mixture of water and abrasive to cut hard materials
such as metal or granite, while the terms pure
waterjet and water-only cutting refer to waterjet
cutting without the use of added abrasives, often
used for softer materials such as wood or rubber.
17. Abrasive Water Jet Machining
The primary difference between pure and
abrasive waterjet cutting is whether additives
are mixed into the pressurized water that
streams from the machine nozzle. In pure
waterjets, the pressure of the water alone,
when forced through a tiny orifice, is used to
cut through materials like foam .
18. Abrasive Water Jet Machining
• Extremely fast set-up and programming
• Very little fixturing for most parts
• Machine virtually any 2D shape on any
material
• Very low side forces during the machining
• Almost no heat generated on the part
• Machine thick plates
Advantages of AWJM
20. Electro-Chemical
Machining (ECM)
The process of
removing a metal
or alloy from a material,
through electrolytic
action.
Works on the principle
of electrolysis .
Low DC voltage, very
High current (700A)
21. Electrochemical grinding
Combines electrochemical machining
with conventional grinding
◦ Grinding wheel is the cathode
◦ Metal bonded wheel with diamond or
Al2O3 abrasive
◦ Majority of material removal from
electrolytic action (95%) therefore very
low wheel wear
◦ Much faster than conventional grinding
23. Electro-Jet Drilling
It is a process in which a negatively
charged stream of acid electrolyte is
impinged on the workpiece to form a
hole
Electro jet drilling (EJD) is one such
technique, which is finding ever-
increasing applications in several
industries including aerospace,
medical, automobile and micro
fabrication (electronic and computers).
26. Electrode Discharge Machining (EDM)
The tool acts as a cathode (typically graphite) is immersed in a
Dielectric fluid with conductive workpiece
DC voltage (~300V) is applied.
As voltage builds up over gap between workpiece and tool,
eventually you get dielectric breakdown (sparking at around
12,000 deg F)
The sparking erodes the workpiece in the shape of the tool
Cycle is repeated at 200,000-500,000 Hz
28. Laser Beam Machining
Lasers are high intensity focused light
sources
◦ CO2
Most widely used
Generally more powerful that YAG lasers
Cutting operations commonly
◦ Nd:YAG (Neodymium ions in an Yttrium Aluminum
Garnet)
Less powerful
Etching/marking type operations more commonly
Limited in depth of cut (focus of light)
Would limit workpiece to less than 1 inch (<
½” typically)
30. Electron Beam Machining
Electron-beam machining (EBM) is a
process where high-
velocity electrons concentrated into a narrow
beam are directed toward the work piece,
creating heat and vaporizing the material.
EBM can be used for very accurate cutting or
boring of a wide variety of metals.
The process of heating by electron beam is
used for annealing, welding or metal removal.
33. Chemical Milling
Chemical milling or industrial etching is the
subtractive manufacturing process of using
baths of temperature-regulated etching
chemicals to remove material to create an
object with the desired shape.
It has applications in the printed circuit
board and semiconductor fabrication
industries. It is also used in the aerospace
industry to remove shallow layers of material
from large aircraft components, missile skin
panels, and extruded parts for airframes
35. Photo Chemical Milling
Photochemical machining (PCM), or photo
etching, is a chemical milling process used
to fabricate sheet metal components using
a photo resist and etchants to
corrosively machine away selected areas.
Industrial applications include fine screens
and meshes, apertures and masks, battery
grids, fuel
cell components, sensors, springs, pressure
membranes, heat sinks, and much more.